class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m = obstacleGrid.size();
        int n = obstacleGrid[0].size();
        vector<vector<int>> dp(m,vector<int>(n));

        dp[0][0] = obstacleGrid[0][0]==1 ? 0 : 1;
        if(dp[0][0] == 0) return 0;
        for(int i = 1; i < n; i++)
        {
            if(obstacleGrid[0][i] == 1)
                dp[0][i] = 0;
            else
                dp[0][i] = dp[0][i-1];

        }
        for(int i = 1; i < m; i++)
        {
            if(obstacleGrid[i][0] == 1)
                dp[i][0] = 0;
            else
                dp[i][0] = dp[i-1][0];
        }

        for(int i = 1; i < m; i++)
        {
            for(int j = 1; j < n; j++)
            {
                if(obstacleGrid[i][j] == 1)
                {
                    dp[i][j] = 0;
                }
                else
                {
                    dp[i][j] = dp[i-1][j] + dp[i][j-1];
                }
            }
        }

        return dp[m-1][n-1];
    }
};